I understand the concept about the salts, and I do appreciate the explanation.
But not everyone shoots using black powder.
And the other powders have totally different formulas.
Also, the carbon portion of the fouling are not all salts, are they?
So using mineral oil as a cleaner is not only about absorbing BP salts, but about releasing them and carbon from the surface of the metal physically with the help of a combination lubricant/solvent/cleaner.
So the question then becomes whether, in addition to the carbon, can any of the salts be removed by physically rubbing them off with a mineral oil laden patch or brush, and what percentage of them will be left behind?
How could the amount of residual salts be measured using a uniform method?
I don't know of many folks who claim to use a single cleaner either, even if the cleaner is mostly water other ingredients are usually mixed in.
I use multiple cleaning agents and I don't shoot with black powder or use water.
And I was mostly responding to the assetion that mineral oil is not a cleaner or a solvent.
If over 90% of BP residue is carbon ash, then mineral oil should clean better than 90%.
Some folks use spit for a wet patch, others use alcohol.
Some folks mix Ballistol with water and spray it on.
If substitute powder residues don't contain the same salts, then mineral oil can be used as a solvent/cleaner, no doubt with some kind of effectiveness.
I just wanted to keep the discussion about mineral oil real and to not so readily dismiss it as being worthless as a cleaner which is the question in the OP.